SEPTEMBER 15, 2026
Live Feed
Back to database
Case File

CVE-2026-77640

LOW · CVSS 3.7 EPSS 0.22%

Source: NVD + CISA KEV + EPSS · Published 2026-08-20 · Last synced 2026-09-15

CyberRota Analysis

AI-Generated

The vulnerability affects the Tor software prior to version 0.4.9.9, where an infinite loop can occur when decompressing a truncated zlib/gzip stream, leading to potential denial-of-service conditions. This issue arises from the mishandling of the Z_BUF_ERROR response, which causes the system to enter an endless retry loop. Users and administrators of Tor should prioritize this update to mitigate the risk of service interruptions.

CVE
CVE-2026-77640
Severity
LOW
CVSS
3.7
EPSS
0.22%

Original NVD Description

tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip stream with done=1. A truncated stream never reaches Z_STREAM_END, causing zlib to return Z_BUF_ERROR with no input remaining, which buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-021.

Related CVEs

Other vulnerabilities affecting the same vendor(s)